Myxofibrosarcoma presenting in the skin: clinicopathological features and differential diagnosis with cutaneous myxoid neoplasms.

Myxofibrosarcoma (myxoid malignant fibrous histiocytoma) is one of the most common fibroblastic sarcomas in the older patient, where it can sometimes present with anatomically deceptive boundaries. Myxofibrosarcoma is now fully characterized as a distinctive and definable pathologic entity. Clinically there is a tendency for predominantly subcutaneous, multinodular, diffusely infiltrative growth, which may extend to the overlying dermis and present as a cutaneous lesion. Histologically myxofibrosarcoma comprises a spectrum ranging from hypocellular low-grade myxoid to high-grade pleomorphic sarcoma. We report herein 6 cases of myxofibrosarcoma each with dermatological presentation as a cutaneous nodule. The dermal component in each of the lesions was low- to intermediate-grade and predominantly myxoid resulting in confusion with benign myxoid neoplasms in small biopsy specimens. The purpose of this series is to focus the attention of workers in dermatology on a subject rarely discussed in dermatopathology literature: the cutaneous presentation of myxofibrosarcoma and the potential for clinical and histologic misinterpretation, as benign dermal lesions.